In transporting commodities from one location to another with trailers, rear self-discharge trailers are typically utilized to transport bulk commodities, such as sand, coal, and coke. However, rear self-discharge trailers are typically not utilized to transport general commodities as commodities must generally be loaded onto a rear self-discharge trailer by “dumping” the commodities over the side of trailer. As such, flat bed or other similar trailers are often utilized to transport general commodities, and these commodities are then tied down to the trailer for transport. One problem with simply tying down a load of commodities to a trailer, however, is that the load is exposed to the weather, which can damage the commodities. Additionally, road debris or other foreign objects are commonly thrown into the air by the trucks pulling the trailer, or the wheels of the trailers themselves, and can further damage the commodities that are being transported.
Recognizing the deleterious effects that may result from tying a load to a flat bed trailer, various enclosure systems have been developed to protect the loads from the weather or from the debris that can strike the load in transit. Some of these enclosure systems have involved simple designs, such as a tarp that is merely tied over the load and used to provide a protective barrier for the commodities. Other enclosure systems, however, are considerably more detailed. For example, U.S. Pat. No. 4,711,484 describes a tarp cover system for flat bed trailers that makes use of a number of inverted U-shaped bow members that are longitudinally extendable and can be used to cover the entirety of the flat bed of a trailer. When a trailer equipped with such a tarp cover system is loaded, the U-shaped members and the tarp can be pulled into a collapsed position for loading and, subsequently, the U-shaped members and the tarp can then be expanded such that the enclosure system covers and protects the load in transit.
Despite the advantages that may be obtained by employing an enclosure system in a flat bed trailer, current enclosure systems are still not suitable for transporting bulk commodities. For instance, the tarp cover system described in U.S. Pat. No. 4,711,484 could not be used to carry a load of coal as the portion of the tarp cover system attached to the flat bed trailer and the tarp itself would not provide the required mechanical strength for carrying such a load.
In any event, a trailer has yet to be designed that combines the utility and beneficial properties of a rear self-discharge trailer with the utility and beneficial properties of a flat bed trailer covered with an enclosure system, such that a trailer can be provided that not only protects a load of commodities from the weather and various debris, but also is capable of carrying bulk commodities such as coal.